Introductory Biostatistics

there are two continuous independent variables (i.e., preoperative fac-

tors), age at diagnosis and level of serum acid phosphatase (100; called

‘‘acid’’), and three binary variables: x-ray reading, pathology reading

(grade) of a biopsy of the tumor obtained by needle before surgery, and

a rough measure of the size and location of the tumor (stage) obtained

by palpation with the fingers via the rectum. For these three binary

independent variables, a value of 1 signifies a positive or more serious

state and a 0 denotes a negative or less serious finding. In addition, the

sixth column presents the finding at surgery—the primary outcome of

interest, which is binary, a value of 1 denoting nodal involvement, and a

value of 0 denoting no nodal involvement found at surgery.

TABLE E2.32

X-

ray Grade Stage Age Acid Nodes

X-

ray Grade Stage Age Acid Nodes

01 16440000 060780

00 16340000 052830

10 06546000 167950

01 06747000 056980

0 0 0 66 48 0 0 0 1 61 102 0

0 1 1 65 48 0 0 0 0 64 187 0

00 06049010 158481

00 05149000 165491

00 06650011 157511

00 05850001 050561

01 05650011 067671

00 16150000 167671

01 16450001 157671

00 05652001 145701

00 06752000 146701

10 04955010 151721

01 15255011 160761

00 06856011 156781

01 16659011 150811

10 06062000 056821

00 06162000 163821

11 15963011 165841

00 05165010 164891

01 15366001 059991

0 0 0 58 71 0 1 1 1 68 126 1

0 0 0 63 75 0 1 0 0 61 136 1

00 153760

Note:This is a very long data file; its electronic copy, in a Web-based form, is available

from the author upon request.

104 DESCRIPTIVE METHODS FOR CONTINUOUS DATA